She is a kindergarten teacher who brings wild Pokémon she and her Sylveon have befriended to the kindergarten she works at to give the children experience with Pokémon. One day, though, she was lucky enough to meet a group of Pokémon Trainers; namely, Ash and his friends. She challenged Ash to a battle when they locked eyes with the condition that Ash comes with her if she wins, using Sylveon against Ash's Froakie. Although Froakie put up a good fight against the Intertwining Pokémon, Sylveon infatuated Froakie with Attract, rendering them defenseless against Draining Kiss. As a result, Ash lost and had to accompany her to the kindergarten. Ash enthusiastically allowed the children to pet Pikachu and encouraged Serena, Clemont, and Bonnie to let their Pokémon meet the children.

All the children happily interacted with the gang's Pokémon with the exception of a boy named Randall, who was terrified of Pokémon due to a previous negative experience. Soon, Team Rocket arrived disguised as a volunteer entertainment troupe, stole Pikachu and Sylveon and drove off in a truck. Randall and Froakie were accidentally taken along for the ride and Ash clung to the back of the truck in an effort to rescue the stolen Pokémon. Penelope decided to follow the truck once she realized Randall was missing, with Serena, Clemont and Bonnie coming with her; she was led to the truck by Fletchling. By the time they arrived at Team Rocket's hideout, Ash had already broken Pikachu and Sylveon out of the glass cages with Froakie and Randall's help and sent Team Rocket blasting off.

Later on, she waved the gang goodbye with Sylveon, Randall, the principal, and the other kindergartners.

Pokémon

Sylveon

Sylveon is Penelope’s partner Pokémon. It was sent out against Froakie when Penelope challenged Ash to a battle, proving itself to be a skilled battler. It was able to defeat the Bubble Frog Pokémon by infatuating it with Attract and finishing it off with Draining Kiss.

Later, it was stolen along with Pikachu by Team Rocket, but was rescued by Ash, Froakie and Randall and helped the three free Pikachu. Whilst Ash battled Team Rocket, it protected Randall from Pumpkaboo and Inkay's attacks. Immediately afterwards, it was reunited with its Trainer.